A NEW DISCOVERY

Hokitika Guardian, 30 July 1921, Page 4

A NEW DISCOVERY

TELEPHONE DEVICE FOR aircraft. LONDON, June 9. What scents t<> lie the nearest approach to the insolvable problem of perpetual motion was demonstrated in a lecture before the Institution of Electrical Engineers by two Danish engineers, Mr Alfred Johnson and Mr Knud Ralibek, who had been invited to come to London to repeat their experiments. They noticed bv'HOlT that when an electric potential difference is applied between a solid body, consisting of c-ei-tain badly conducting materials e.g.. various minerals, and a conducting body, such as a metal disc, resting on the former body, strong adhesive forces are develoed, and these they attribute to electrostatic attraction between the two surfaces. They find that an attraction of several pounds can he obtained between a thick- lithographic stone, fitted with an electrode at the back, and a metal disc 2iu in diameter resting thereon, on the application of a potential diffence of 4-10 volts with a very small current. The disc will

then lift the stone in a manner exactly similar to that in which an electromagnet can he lifted by its armntuio. and the stone will drop when the current is interrupted. Similar qualities are exhibited by flint- agate, some kinds of slate, and many other minerals and salts, ns well as by many organic- substances, such as animal membranes, skin, gelatine, and bone; bid the experiment, cannot bo carried out with true insulators like glass, mica, or hard rubber, because the necessary current will not flow. What this means in practice is that a- tew thousand extra miles would make little or no difference in sendng a wireless message. The rate of receiving wireless telegraph messages can be speeded up to several hundred words n minute, and so forth. The possibilities of. the discovery when fully investigated will undoubtedly lend to fresh advances in many branches of commercial electricity. TELEPHONES ON AI BCR Ah I.

, Mr William Duhilicr. a pioneer of 1 wireless telephony and telegraphy, who has just, arrived in this country, explains some of the latest of wireless developments. He has brought with him an apparatus designed to improve \ and simplify wireless telephony from 1 aircraft. He explained that up to the i present the difficulty of currying out- ' efficient conversational telephony from 1 aircraft has lain in the generating of 1 the current. This is produced by tire | -operation of a dynamo worked by a 1 propeller, which is revolved by the air stream forced against it in the flight of the aircraft. Variations in the power produced, however, result from vaiiations in the speed at which the aeroplane may he flying. The apparatus in question is designed to correct this defect-. Tt consists of a streamlined aluminium boss fitted with a single fin. | The fin operates against a strong spring, and is sensitive to wind pres- . sure, its adjustment to the radio sot maintaining the flow of electric current at an even rate, whatever changes in speed may he made by the airship or i aeroplane. Mr Duhilicr is convinced that there will he entirely satisfactory wireless telephone communication between London and New York within the next few years. Tie has boon carrying out experiments on land and sea recently with this moans of communication. He described bow three days a week regularly ships in the Pacific were talking with ships in the Atlantic by wireless relaved over land lines.

“The wireless telephone i.s 6.1 ready greatly used in the States.” said Mr Dubilier. “not. only for conversations overseas, hut for ordinary trunk calls inland. The telephone subscriber do s not know, in many cases, whether lie is talking over wires or not. You could have just the same system in this coun-

try. Now that it is possible so minutely to adjust the waves there ought to he no fear of <-ougestion. Incidentally. the Germans are miles behind us and you in wireless work. For the modern condenser you must have mica and they could get none of it during the war.”